Wood preservation

An organic solvent-free process for treating a pressure permeable wood species selected from the group consisting of pines and firs which comprises the steps of:

• a. preparing an aqueous solution of tannin extract obtained from one or more plant materials selected from the group consisting of bushes, trees, shrubs, bark, heartwood, leaves, roots, pods or nuts from one or more plant species selected from the group consisting of acacia negra, quebracho, chestnut, myrobalan, mangrove, tara, eucalyptus, divi divi, sumac, cypress, gambier, or chestnut oak;
• b. impregnating said wood species with said aqueous extract solution;
• and
• c. subsequently impregnating said wood species with an aqueous solution of a fixative selected from the group consisting of non-ionic surface active agents and cationic surface active agents, wherein said aqueous extract solution comprises from about 1 to about 10 weight percent of tannin extract and wherein said aqueous fixative solution comprises from about 0.1 to about 5 weight percent of said fixative.

The process for treating a pressure permeable wood species selected from the group consisting of pines and firs which comprises the steps of:

• a. preparing an aqueous solution of tannin extract obtained from one or more plant materials selected from the group consisting of bushes, trees, shrubs, bark, heartwood, leaves, roots, pods or nuts from one or more plant species selected from the group consisting of acacia negra, quebracho, chestnut, myrobalan, mangrove, tara, eucalyptus, divi divi, sumac, cypress, gambier, or chestnut oak;
• b. impregnating said wood species with said aqueous extract solution;
• c. subsequently impregnating said wood species with an aqueous solution of a fixative selected from the group consisting of non-ionic surface active agents and cationic surface active agents, wherein said aqueous extract solution comprises from about 1 to about 10 weight percent of tannin extract and wherein said aqueous fixative solution comprises from about 0.1 to about 5 weight percent of said fixative;
• and
• d. impregnating said wood species with an aqueous solution of a metallic salt selected from the group consisting of zinc, aluminum, chromium, iron and copper salts and wherein said aqueous metallic salt solution contains from about 1 to about 10 percent of said metallic salt.